U.S. patent application number 16/520748 was filed with the patent office on 2019-12-05 for solvent-based adsorbent regeneration for onboard octane on-demand and cetane on-demand.
This patent application is currently assigned to Saudi Arabian Oil Company. The applicant listed for this patent is Saudi Arabian Oil Company. Invention is credited to Amer A. Amer, Junseok Chang, Esam Zaki Hamad, Eman AbdelHakim A.M. Tora.
Application Number | 20190368451 16/520748 |
Document ID | / |
Family ID | 63963406 |
Filed Date | 2019-12-05 |
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United States Patent
Application |
20190368451 |
Kind Code |
A1 |
Hamad; Esam Zaki ; et
al. |
December 5, 2019 |
SOLVENT-BASED ADSORBENT REGENERATION FOR ONBOARD OCTANE ON-DEMAND
AND CETANE ON-DEMAND
Abstract
A vehicular propulsion system, a vehicular fuel system and a
method of producing fuel for an internal combustion engine. A
separation unit that makes up a part of the fuel system includes
one or more adsorbent-based reaction chambers to selectively
receive and separate at least a portion of onboard fuel into
octane-enhanced and cetane-enhanced components. Regeneration of an
adsorbate takes place through interaction with a solvent, while
subsequent separation allows the solvent to be reused. A controller
may be used to determine a particular operational condition of the
internal combustion engine such that the onboard fuel can be sent
to one or more combustion chambers within the internal combustion
engine without first passing through the separation unit, or
instead to the separation unit in situations where the internal
combustion engine may require an octane-rich or cetane-rich
mixture.
Inventors: |
Hamad; Esam Zaki; (Dhahran,
SA) ; Tora; Eman AbdelHakim A.M.; (Faisal, EG)
; Amer; Amer A.; (Dhahran, SA) ; Chang;
Junseok; (Dhahran, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Saudi Arabian Oil Company |
Dhahran |
|
SA |
|
|
Assignee: |
Saudi Arabian Oil Company
Dhahran
SA
|
Family ID: |
63963406 |
Appl. No.: |
16/520748 |
Filed: |
July 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15939971 |
Mar 29, 2018 |
10408139 |
|
|
16520748 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 21/16 20130101;
C10L 2200/0423 20130101; F02M 27/00 20130101; B01D 15/424 20130101;
C10L 2200/0446 20130101; F02M 37/22 20130101; C10G 25/003 20130101;
C10L 2270/026 20130101; C10L 2290/58 20130101; F02M 37/0064
20130101; C10L 2270/023 20130101; F02D 19/0697 20130101; F02D
41/0025 20130101; F02D 2200/021 20130101; B01D 15/34 20130101; C10G
25/03 20130101; C10L 1/06 20130101; C10G 21/28 20130101; B01D
15/3804 20130101; F02D 19/0671 20130101; F02D 19/0649 20130101;
C10L 1/08 20130101; C10L 2290/542 20130101 |
International
Class: |
F02M 37/22 20060101
F02M037/22; B01D 15/42 20060101 B01D015/42; B01D 15/34 20060101
B01D015/34; B01D 15/38 20060101 B01D015/38; F02D 41/00 20060101
F02D041/00; F02D 19/06 20060101 F02D019/06; C10L 1/06 20060101
C10L001/06; C10L 1/08 20060101 C10L001/08 |
Claims
1. A vehicular propulsion system comprising: an internal combustion
engine comprising at least one combustion chamber; and a fuel
system comprising: a fuel supply tank for containing an onboard
fuel; a separation unit in fluid communication with the fuel supply
tank, the separation unit comprising at least one adsorbent-based
reaction chamber that is configured to receive and separate at
least a portion of the onboard fuel into an adsorbate and a
remainder; a solvent supply in fluid communication with the
separation unit and containing at least one solvent therein to
convert at least a portion of the adsorbate into a desorbate; and a
solvent regeneration unit configured to separate at least a portion
of the at least one solvent from the desorbate such that during
operation of the internal combustion engine and the fuel system, at
least one of the-onboard fuel, separated desorbate and remainder is
conveyed to the combustion chamber.
2. The vehicular propulsion system of claim 1, further comprising:
a plurality of sensors that are configured to acquire operational
parameters associated with the internal combustion engine; and a
controller responsive to signals conveyed from the plurality of
sensors in order to: make a determination of an operational
condition of the internal combustion engine; and instruct the fuel
system to convey at least one of the-onboard fuel, separated
desorbate and remainder to the combustion chamber depending on the
operational condition.
3. The vehicular propulsion system of claim 2, wherein the
operational condition of the internal combustion engine comprises
at least a first operational condition and a second operational
condition such that: upon the determination that the internal
combustion engine is in its first operational condition, at least a
portion of the onboard fuel is conveyed to the combustion chamber
without first passing through the separation unit; and upon the
determination that the internal combustion engine is in its second
operational condition, at least a portion of the onboard fuel is
conveyed to the combustion chamber after having passed through the
separation unit.
4. The vehicular propulsion system of claim 2, wherein the
operational condition of the internal combustion engine is such
that the controller instructs the fuel system to convey a plurality
of the at least one onboard fuel, separated desorbate and remainder
to the combustion chamber.
5. The vehicular propulsion system of claim 4, wherein the at least
one of the onboard fuel, separated desorbate and remainder comprise
an octane-rich component and a cetane-rich component such that upon
a load that corresponds to the operational condition of the
internal combustion engine, the controller instructs the fuel
system to convey one or the other of the octane-rich component and
the cetane-rich component to the combustion chamber.
6. The vehicular propulsion system of claim 1, wherein the at least
one adsorbent-based reaction chamber contains an affinity-based
adsorbent.
7. The vehicular propulsion system of claim 1, wherein the at least
one adsorbent-based reaction chamber contains a size
selective-based adsorbent.
8. The vehicular propulsion system of claim 1, wherein the at least
one adsorbent-based reaction chamber contains both an
affinity-based adsorbent and a size selective-based adsorbent.
9. A vehicular fuel system for converting an onboard fuel into an
octane-rich component and a cetane-rich component, the fuel system
comprising: a fuel supply tank for containing an onboard fuel; a
separation unit in fluid communication with the fuel supply tank,
the separation unit comprising at least one adsorbent-based
reaction chamber that is configured to receive and separate at
least a portion of the onboard fuel into an adsorbate and a
remainder; a solvent supply in fluid communication with the
separation unit and containing at least one solvent therein to
convert at least a portion of the adsorbate into a desorbate; and a
solvent regeneration unit configured to separate at least a portion
of the at least one solvent from the desorbate such that during
operation of the internal combustion engine and the fuel system, at
least one of the-onboard fuel, separated desorbate and remainder is
conveyed to the combustion chamber.
10. A method of producing fuel for an internal combustion engine,
the method comprising: conveying onboard fuel to a separation unit
that makes up a portion of a fuel system; contacting the fuel with
an adsorbent situated within the separation unit such that at least
a portion of the fuel is converted into an adsorbate and at least a
portion of the fuel is converted into a remainder; reacting at
least one solvent with the adsorbate such that at least a portion
of the adsorbate is converted into a desorbate; separating the
desorbate from the at least one solvent; and conveying at least one
of the onboard fuel, separated desorbate and remainder to a
combustion chamber within the internal combustion engine.
11. The method of claim 10, further comprising: sensing at least
one operational parameter associated with the fuel system and the
internal combustion engine; and using a controller to determine an
engine operational condition that is selected from a plurality of
operational conditions based on the at least one sensed operational
parameter such that the conveying at least one of the onboard fuel,
separated desorbate and remainder to a combustion chamber within
the internal combustion engine is performed based on the determined
operational condition.
12. The method of claim 11, wherein the engine operational
condition comprises: a first operational condition such that at
least a portion of the onboard fuel is conveyed to the combustion
chamber without first passing through the separation unit; and a
second operational condition such that at least a portion of the
onboard fuel is conveyed to the combustion chamber after having
passed through the separation unit.
13. The method of claim 11, wherein the operational condition
corresponds to at least one of a predetermined temperature, load
and rotational speed of the internal combustion engine.
14. The method of claim 11, further comprising using a controller
to determine that the engine operational condition corresponds to a
situation where at least one of a first enriched product tank and a
second enriched product tank that are used to contain a respective
separated desorbate and remainder is substantially empty.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
patent application Ser. No. 15/939,971 filed on Mar. 29, 2018, the
entire disclosure of which is hereby incorporated herein by
reference.
BACKGROUND
[0002] The present disclosure relates generally to a vehicular fuel
system for selectively separating an onboard fuel into octane-rich
and cetane-rich components, and more particularly to such a system
that promotes adsorption and solvent-based desorption as part of
such onboard fuel separation in such a way to reduce the size,
weight and complexity associated with such fuel separation
activities.
SUMMARY
[0003] Within the realm of internal combustion engines (ICEs) used
for vehicular propulsion, it is the four-cycle variant (with its
intake, compression, combustion and exhaust strokes) that is most
commonly in use, where the combustion is typically achieved through
either a spark ignition (SI) mode or compression ignition (CI) mode
of operation. In SI-based modes, a mixture of air and fuel
(typically octane-rich gasoline) is introduced into a combustion
chamber for compression and subsequent ignition via spark plug. In
CI-based modes, fuel (typically cetane-rich diesel fuel) is
introduced into the combustion chamber where the air is already
present in a highly compressed form such that the elevated
temperature within the chamber that accompanies the increased
pressure causes the fuel to auto-ignite. Of the two, the CI mode
tends to operate with greater efficiency, while the SI mode tends
to operate with lower emissions.
[0004] Various engine concepts or configurations may mimic the
relatively low emissions of an SI mode of operation while
simultaneously satisfying the high efficiency operation of a CI
mode of operation. Such concepts go by various names, and include
gasoline direct injection compression ignition (GDCI), homogenous
charge compression ignition (HCCI), reactivity controlled
compression ignition (RCCI), as well as others. In one form, a
single fuel may be used, while in others, multiple fuels of
differing reactivities, usually in the form of selective
octane-enrichment or cetane-enrichment, may be introduced. While
performing octane on demand (OOD) or cetane on demand (COD) as a
way of fueling these engines is possible, such activities may be
fraught with problems. For example, having the respective
octane-enriched or cetane-enriched portions be in either
pre-separated form involves the parallel use of at least two
onboard storage tanks and associated delivery conduit. In addition,
the time and complexity associated with vehicle refueling activity
in this circumstance renders the possibility of operator error
significant. Likewise, OOD or COD generation once the single market
fuel is already onboard may require distillation or membrane-based
permeation-evaporation (pervaporation) activities that are
accompanied by significant increases in size, weight and overall
complexity of the onboard fuel-reforming infrastructure. These
difficulties are particularly acute as they relate to achieving a
heat balance associated with the underlying fuel enrichment
activities. As such, a simplified approach to integrating such
infrastructure into an onboard fuel separation system is
warranted.
[0005] According to one embodiment of the present disclosure, a
vehicular propulsion system is disclosed. The propulsion system
includes an ICE with one or more combustion chambers and a fuel
system for converting an onboard fuel into octane-rich and
cetane-rich fuel components. The fuel system includes an onboard
source of fuel in the form of a fuel supply tank (also referred to
herein as an onboard fuel tank, main tank, market fuel tank or the
like), fuel conduit, a separation unit, a solvent supply, a solvent
regeneration unit and a pair of enriched product tanks. The fuel
conduit provides fluid connectivity between at least some of the
fuel supply tank, separation unit and enriched product tanks. The
separation unit includes one or more adsorbent-based reaction
chambers that can selectively receive and separate at least a
portion of the onboard fuel into an adsorbate and a remainder. The
solvent supply works in conjunction with the separation unit such
that one or more solvents contained within the solvent supply may
be brought into contact with the adsorbate that forms in the
reaction chambers such that the solvent acts to convert at least a
portion of the adsorbate into a desorbate so that the desorbed
compound may be removed. After the solvent removes the desorbate
from the reaction chamber, the solvent-desorbate mixture is
introduced to a solvent regeneration unit that can separate the
solvent from the desorbate. In this way, the separated desorbate
may then be routed either to a first of the enriched product tank
for storage, or directly to the combustion chamber, depending on
the need. A second of the enriched product tanks is fluidly coupled
to the reaction chamber (or chambers) for receiving and containing
the remainder of the onboard fuel that did not get adsorbed. During
operation of the ICE, the fuel system is in fluid communication
with the ICE such that one or more of the supply tank and the first
and second enriched product tanks provide their respective onboard
fuel, separated desorbate and remainder to the one or more
combustion chambers.
[0006] According to another embodiment of the present disclosure, a
vehicular fuel system for converting an onboard fuel into
octane-rich and cetane-rich components is disclosed. The fuel
system includes a supply tank for containing the onboard fuel, fuel
conduit in fluid communication with the supply tank, a separation
unit in fluid communication with the supply tank through the fuel
conduit, a solvent supply in fluid communication with the
separation unit and containing one or more solvents to convert at
least a portion of the adsorbate into a desorbate, a solvent
regeneration unit configured to separate at least a portion of the
solvent from the desorbate, and a pair of enriched product tanks
the first of which receives and contains the portion of the
desorbate that has been separated from the one or more solvents,
and a second of which receives and contains the non-adsorbed
remainder from the onboard supply of fuel that was delivered to one
or more adsorbent-based reaction chambers that make up the
separation unit.
[0007] According to yet another embodiment of the present
disclosure, a method of producing fuel that is used in an ICE to
provide propulsive power to a vehicle is disclosed. The method
includes conveying an onboard (that is to say, market) fuel to a
separation unit, contacting the fuel with an adsorbent situated
within the separation unit such that at least some of the fuel is
converted into an adsorbate and at least some of the fuel is
converted into a remainder, reacting one or more solvents with the
adsorbate such that at least some of the adsorbate is converted
into a desorbate, separating the desorbate from the solvent or
solvents, and conveying one or more of the onboard fuel, separated
desorbate and remainder to a combustion chamber within the ICE.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] The following detailed description of specific embodiments
of the present disclosure can be best understood when read in
conjunction with the following drawings, where like structure is
indicated with like reference numerals and in which:
[0009] FIG. 1 shows a vehicle with a partial cutaway view of an
engine in accordance with one or more embodiments shown or
described;
[0010] FIG. 2 shows a simplified cutaway view of a cylinder of the
engine of FIG. 1 along with a controller in accordance with one or
more embodiments shown or described; and
[0011] FIG. 3 illustrates a simplified view of an onboard fuel
separation system in accordance with one or more embodiments shown
or described.
DETAILED DESCRIPTION
[0012] In the present disclosure, a fuel system with
adsorption-based separation may be used to first split an onboard
fuel into OOD or COD streams and then to regenerate the adsorbent
by solvent desorption of the adsorbate. Within the present context,
the term "adsorbate" and its variants include those portions of the
onboard fuel that interact by surface retention (rather than by
bulk absorption) with the adsorbent, while the term "desorbate" and
its variants include those portions of the adsorbate that are
subsequently liberated from the adsorbent as a result of the
solvent-based regenerating action. The adsorption can take
advantage of one or both of two specific mechanisms: (1) employing
differing functional groups that attract specific adsorbates (such
as aromatics, cyclic and optional oxygenates) that are present in
the onboard fuel supply in what is referred to in the present
disclosure as an affinity-based adsorbent; and (2) using a
molecular sieve to selectively pass certain smaller (that is to
say, linear) molecules while retaining larger (that is to say,
branched) ones in what is referred to in the present disclosure as
a size selective-based adsorbent. Examples of the first type of
adsorbent include activated carbon, silica, and alumina, as well as
some types of zeolites and functionalized porous material in
general, while examples of the second type include zeolites, metal
organic frameworks and structured porous material. Accordingly, the
type of sorbent material used for a particular adsorption reaction
may be based on the way the sorbent functions where affinity-based
sorbents are useful for generating octane-rich fuel components from
the market fuel owing at least in part to the specific
functionality (oxygen atom, aromatic, or double bond) attributes of
such components. As such, affinity-based adsorbents use this
functionality to preferentially capture octane-rich fuel
components. It is noted that there are some high cetane number (CN)
additives that have functional groups such that if present in the
market fuel, the affinity-based sorbents could capture them as
well; nevertheless, the presence of such materials is deemed to be
low enough to not significantly impede the ability of
affinity-based adsorbents to provide an adsorbate with a higher
research octane number (RON) than that present in the market fuel.
Likewise, size selective-based sorbents are preferred for
generating cetane-rich fuel components because of the linear
structure (and relatively small molecular footprint) of alkanes and
other such components in commercial fuels. As such, size
selective-based adsorbents take advantage of the relatively small
aromatics with single benzene rings (such as benzene, toluene and
xylene) that are prevalent in gasoline and the larger aromatics in
the form of polycyclic (or polynuclear) aromatic hydrocarbons
(PAHs) including naphthalene and its derivatives in diesel fuel to
preferentially capture cetane-rich fuel components.
[0013] Referring initially to FIG. 3, details associated with the
use of solvent-based desorption for performing onboard COD and OOD
operations while avoiding complicated component redundancy for fuel
system 200 are shown. By taking advantage of existing onboard fuel
delivery and ICE 150 operating infrastructure, any on-vehicle
adsorbing and regenerating activities can be achieved without
requiring additional heating or cooling equipment or
efficiency-decreasing activities such as those associated with the
high pressure operation of membrane-based pervaporation equipment.
The fuel system 200 includes a network of pipes, tubing or related
flow channels--along with various valves to preferentially permit
or inhibit the flow of the onboard fuel and its byproducts of
fuels, depending on the need--that make up conduit 210. The solvent
supply 230 is coupled to the market fuel M being delivered from the
tank 220 through conduit 210 so that if the market fuel M that is
being delivered to either the combustion chamber 156 or separation
unit 240 is in need of being enriched with either octane or cetane,
it can receive such enrichment from the cooperation of the solvent
supply 230 and the separation unit 240. In one form, the solvent
supply 230 may include a solvent tank 232 for holding an eluent in
the form of solvent V such as ethylene glycol, propylene carbonate
or the like, while a pump 234 may be used to pressurize and deliver
the solvent V contained in the solvent tank 232 to the reaction
chambers 242, 244 of separation unit 240.
[0014] Within the present context, a remainder R (also referred to
as a filtrate) is the portion of the market fuel M being exposed to
the adsorbent 242A, 244A in the reaction chambers 242, 244 that
does not get adsorbed, such as through one or both of the
previously-discussed functional group or molecular sieve modes of
adsorbent 242A, 244A operation Likewise, the adsorbate A (also
referred to as an eluate) is the portion of the market fuel M being
exposed to the adsorbent 242A, 244A in the reaction chambers 242,
244 that does get adsorbed, while the solvent V used to desorb the
adsorbate A is referred to as the eluent. In addition, a fuel is
deemed to be octane-rich when it has a concentration of octane
(C.sub.8H.sub.18) or related anti-knocking agent that is greater
than that of the commercially-available market fuel M from which
one or more separation activities discussed herein have been
employed. By way of example, a fuel would be considered to be
octane-rich if it had a RON of greater than about 91-92 or an
anti-knock index (AKI) of greater than about 85-87 for a so-called
regular grade unleaded fuel, with respectively slightly higher
values for mid-grade unleaded fuel and premium unleaded fuel. It
will be understood that there are regional variations in the values
of RON, AKI or other octane indicia, and that the ones expressly
discussed in the previous sentence contemplate a United States
market. Nevertheless, such values will be understood to be suitably
adjusted to take into consideration these regional variations, and
that all such values are deemed to be within the scope of the
present disclosure within their respective region, country or
related jurisdiction. As with octane, a fuel is deemed to be
cetane-rich when it has a concentration of cetane
(C.sub.16H.sub.34) that is greater than that of the
commercially-available market fuel M. By way of example, a fuel
would be considered to be cetane-rich if it had a CN of greater
than about 40-45 as understood in the United States market, with
suitable variations elsewhere.
[0015] Referring next to FIG. 1, a vehicle 100 includes a chassis
110 with a plurality of wheels 120. Chassis 110 may either be of
body-on-frame or unibody construction, and both configurations are
deemed to be within the scope of the present disclosure. The
passenger compartment 130 is formed inside the chassis 110 and
serves not only as a place to transport passengers and cargo, but
also as a place from which a driver may operate vehicle 100. A
guidance apparatus (which may include, among other things, steering
wheel, accelerator, brakes or the like) 140 is used in cooperation
with the chassis 110 and wheels 120 and other systems to control
movement of the vehicle 100. An ICE 150 is situated within an
engine compartment in or on the chassis 110 to provide propulsive
power to the vehicle 100 while a controller 170 interacts with ICE
150 to provide instructions for the latter's operation.
[0016] Referring next to FIG. 2, details associated with the
structure and operation of a portion of the ICE 150 and the
controller 170 are shown. The ICE 150 includes an engine block 151
with numerous cylinders 152, a crankshaft 153 rotatably movable
within the block 151, numerous cams 154 responsive to movement of
the crankshaft 153, a head 155 coupled to the engine block 151 to
define numerous combustion chambers 156. The head 155 includes
inlet valves 157 and exhaust valves 158 (only one of each is shown)
that in one form may be spring-biased to move in response to the
crankshaft 153 through a corresponding one of the cams 154 that are
controlled by either a crankshaft-driven chain, crankshaft-actuated
pushrods or pneumatic actuators (none of which are shown). An air
inlet 159 and an exhaust gas outlet 160 are in selective fluid
communication with each of the combustion chambers 156 through a
fuel injector 161, while a piston 162 is received in each
respective cylinder 152 and coupled to the crankshaft 153 through a
connecting rod 163 so that the reciprocating movement of the piston
162 in response to an SI or CI combustion taking place within the
combustion chamber 156 is converted by the pivoting movement of the
connecting rod 163 and crankshaft 153 to rotational movement of the
crankshaft 153 for subsequent power delivery to the remainder of a
powertrain that is made up of the ICE 150 and transmission, axles,
differentials (none of which are shown) and wheels 120. Although
ICE 150 is shown without a spark ignition device (such as a spark
plug) in a manner consistent with the various CI-based engine
configurations (such as RCCI, HCCI or the like), it will be
understood that in certain operating loads or conditions such as
low loads, cold starts and associated warm-ups, such a spark
ignition may be used (possibly in conjunction with some throttling)
to increase the flame propagation combustion rate while keeping
lower cylinder pressures.
[0017] In one form, ICE 150 is configured as a gasoline compression
ignition (GCI) engine that can be operated with a gasoline-based
fuel. In such case, the presently-disclosed fuel system may be used
to achieve COD through operation on various fuels, including market
gasoline, gasoline without an oxygenate or related anti-knock
compound (also referred to as base gasoline) or gasoline with one
of the many types of alkyls, aromatics or alcohols. In one
non-limiting example, such fuel may have a boiling temperature in
the range of ambient to about 200.degree. C. Unlike an SI mode of
operation where the fuel is substantially injected during the
four-cycle operation's inlet stroke, a GCI mode substantially
injects the fuel during the compression stroke. In one form, the
fuel and air are not fully mixed, which permits phasing of the
combustion process to be controlled by the injection process.
Moreover, the ignition delay permitted by gasoline-based fuels
versus diesel-based fuels will allow for the partially premixed
fuel and air to become more mixed during compression, which in turn
will leave to improvements in combustion. A gasoline-based market
fuel M with some amount of fuel and air premixing helps ensure
suitable fuel-air equivalence ratios for various engine loads and
associated fuel injection timing scenarios. Thus, when configured
as a GCI engine, ICE 150 using a fuel in the gasoline autoignition
range (where for example, the RON is greater than about 60 and the
CN is less than about 30) can provide relatively long ignition
delay times compared to conventional diesel fuels. This in turn can
lead to improved fuel-air mixing and related engine efficiency,
along with lower soot and NOx formation; this latter improvement
leads in turn to a simplified exhaust gas treatment system since
the emphasis is now on oxidizing hydrocarbons and carbon monoxide
in an oxygen-rich environment rather than trying to simultaneously
control NOx and soot. Moreover, when operated as a GCI engine, ICE
150 requires lower fuel injection pressures than diesel-based CI
engines.
[0018] Furthermore, when configured as a GCI engine, ICE 150 may
take advantage of the market fuel M that is in gasoline form,
especially when such fuel requires lower amounts of processing; in
one form (for example, when the market fuel M has an intermediate
RON of between about 70 and 85. Such octane concentrations could
then be adjusted via OOD or COD through the operation of the fuel
system 200 that is discussed in more detail elsewhere in this
disclosure.
[0019] Moreover, unlike HCCI modes of operation where the fuel and
air is fully premixed prior to introduction into the combustion
chamber 156, the GCI embodiment of ICE 150 will permit CI operation
under higher engine loads and compression ratios without concern
over engine knocking. Furthermore, by permitting in-cycle control
of the combustion phasing, an ICE 150 configured as a GCI can take
advantage of fuel injection timing in order to make it easier to
control the combustion process compared to an HCCI configuration
where the combination of temperature and pressure inside the
cylinder may not be precisely known.
[0020] In another form, ICE 150 may be configured as an SI engine
that can be operated with a gasoline-based fuel. In this case, the
presently-disclosed fuel system may be used to achieve OOD through
operation on various fuels, including market gasoline, gasoline
without an oxygenate or related anti-knock compound or gasoline
with one of the many types of alkyls, aromatics or alcohols. In
another form, ICE 150 is configured as a CI engine that can be
operated with a diesel-based fuel. In this case, the
presently-disclosed fuel system 200 may be used to achieve COD
through the use of suitable regenerative solvent-based,
affinity-based and size selective-based adsorbents 242A, 244A.
[0021] Controller 170 is used to receive data from sensors S and
provide logic-based instructions to the various parts of the fuel
system 200 that will be discussed in more detail below. As will be
appreciated by those skilled in the art, controller 170 may be a
singular unit such as shown notionally in FIGS. 1 through 3, or one
of a distributed set of units (not shown) throughout the vehicle
100. In one configuration, controller 170 may be configured to have
a more discrete set of operational capabilities associated with a
smaller number of component functions such as those associated
solely with the operation of the fuel system 200. In such a
configuration associated with only performing functions related to
operation of the fuel system 200, the controller 170 may be
configured as an application-specific integrated circuit (ASIC). In
another configuration, controller 170 may have a more comprehensive
capability such that it acts to control a larger number of
components, such as the ICE 150, either in conjunction with or
separately from the fuel system 200. In this configuration, the
controller 170 may be embodied as one or more electronic control
units (ECUs). It will be appreciated that ASICs, ECUs and their
variants, regardless of the construction and range of functions
performed by the controller 170, are deemed to be within the scope
of the present disclosure.
[0022] In one form, controller 170 is provided with one or more
input/output (I/O) 170A, microprocessor or central processing unit
(CPU) 170B, read-only memory (ROM) 170C, random-access memory (RAM)
170D, which are respectively connected by a bus 170E to provide
connectivity for a logic circuit for the receipt of signal-based
data, as well as the sending of commands or related instructions to
one or more of the components within ICE 150, one or more
components within fuel system 200, as well as other components
within vehicle 100 that are responsive to signal-based
instructions. Various algorithms and related control logic may be
stored in the ROM 170C or RAM 170D in manners known to those
skilled in the art. Such control logic may be embodied in a
preprogrammed algorithm or related program code that can be
operated on by controller 170 such that its instructions may then
be conveyed via I/O 170A to the fuel system 200. In one form of I/O
170A, signals from the various sensors S are exchanged with
controller 170. Sensors S may comprise level sensors, pressure
sensors, temperature sensors, optical sensors, acoustic sensors,
infrared sensors, microwave sensors, timers or other sensors known
in the art for receiving one or more parameters associated with the
operation of ICE 150, fuel system 200 and related vehicular
components. For example, one or more sensors S may be used to
determine if a minimum threshold level of an octane-rich fuel
component or a cetane-rich fuel component is present in a pair of
enriched product tanks 250, 260. Although not shown, controller 170
may be coupled to other operability components for vehicle 100,
including those associated with movement and stability control
operations, while additional wiring such as that associated with a
controller area network (CAN) bus (which may cooperate with or
otherwise be formed as part of bus 170E) may also be included in
situations where controller 170 is formed from various distributed
units.
[0023] In situations where the controller 170 is configured to
provide control to more than just the fuel system 200 (for example,
to the operation of one or more of the ICE 150 or other systems
within vehicle 100), other such signals from additional sensors S
may also be signally provided to controller 170 for suitable
processing by its control logic; one such example may include those
signals where combustion data from the ICE 150 is provided for
control over the mixing or related delivery of the fuel and air.
Likewise, in a manner consistent with various modes of ICE 150
operation, controller 170 may be programmed with drivers for
various components within ICE 150, including a fuel injector driver
170F, a spark plug driver (for SI modes of operation) 170G, engine
valve control 170H and others (not shown) that can be used to help
provide the various forms of fuel introduction to the combustion
chamber 156, including those associated with a
multiple-late-injection, stratified-mixture, low-temperature
combustion (LTC) process as a way to promote smooth operation and
low NOx emissions of ICE 150 over a substantial entirety of its
load-speed range. Within the present context, load-speed mapping of
ICE 150 may be used to identify operating regions such as those
used during cold starts and ICE 150 warm-up, low ICE 150 loads,
medium ICE 150 loads and high ICE 150 loads, where correspondingly
lower amounts of exhaust gas re-breathing takes place through
manipulating the overlap of the intake valve 157 relative to the
exhaust valve 158, possibly in conjunction with other approaches
such as exhaust gas recirculation (EGR) to help provide one or more
of combustion control, exhaust gas emission reductions, or other
operability tailoring for ICE 150.
[0024] In addition to providing instructions for combustion
control, emission reductions or the like, the controller 170
interacts with one or more various components that make up conduit
210, including various actuators, valves and related components to
control the operation of the delivery of fuel from an onboard fuel
supply tank 220 that acts as the main tank for the storage of the
market fuel M (for example, conventional or even low-grade
gasoline, solvent supply 230 and separation unit 240 (all as shown
and described in more detail in conjunction with FIG. 3) in order
to effect the production of OOD or COD required to operate ICE 150
for a given set of load and related operating conditions. In one
form of CAN, the controller 170 could manage the fuel flow from
either the fuel supply tank 220 or the enriched product tanks 250,
260 to the combustion chamber 156 where the two fuels corresponding
to OOD or COD are injected separately, or by blending prior to
being introduced into the combustion chamber 156 at different
ratios depending on load, speed and other optional parameters
associated with operation of ICE 150.
[0025] Significantly, controller 170 is useful in promoting
customizable fuel injection and subsequent combustion strategies
for various ICE 150 configurations where a CI mode of operation is
used. For example, when used in conjunction with a GCI-based (that
is to say, PPCI-based) mode, the controller 170 may instruct the
fuel to be injected in a staged manner late in the compression
phase of the four-cycle operation of ICE 150. In this way, the fuel
charge may be thought of as having both locally stoichiometric and
globally stratified properties. Significantly, because an
octane-rich fuel (for example, gasoline) has a higher volatility
and longer ignition delay relative to a cetane-rich fuel (for
example, diesel), by introducing the octane-rich fuel into the
combustion chamber 156 relatively late in the compression stroke
and taking advantage of the fuel's inherent ignition delay (which
helps to promote additional fuel-air mixing), combustion does not
commence until after the end of the injection. To achieve a
desirable degree of stratification, multiple injections may be
used. By operating under the low temperature combustion (LTC)
conditions that are associated with stratified fuel combustion, a
GCI mode of operation can have significantly reduced NOx production
and soot emissions while achieving traditional diesel-like CI mode
thermal efficiencies. Moreover, such an approach permits the
vehicle 100 to use a version of the onboard market fuel M with a
lower octane than would otherwise be used. This is beneficial in
that such fuel requires a smaller amount of processing than
conventional gasoline and diesel fuels; this in turn reduces the
cost as well as entire well-to-tank emissions of other undesirable
substances, such as CO.sub.2.
[0026] In addition to a GCI mode of operation, such instructions as
provided by controller 170 are particularly beneficial for the
multiple-late injection strategy used for the delivery of fuel in
HCCI, RCCI or related modes of operation of ICE 150, as such
delivery may be optimized when made to coincide with various
sequences in the compression stroke that can be measured by sensors
S as they detect crank angle degree (CAD) values from the
crankshaft 153 to help control when auto-ignition occurs. Within
the present context, the position of the piston 162 within the
cylinder 152 is typically described with reference to CAD before or
after the top dead center (TDC) position of piston 162. The
controller 170 may also base such delivery strategies on other ICE
150 operating parameters such as the previously-mentioned load and
engine speed, as well as the number of times such injection is
contemplated. For example, CAD from 0.degree. to 180.degree.
corresponds to the power stroke, with 0.degree. representing TDC
and 180.degree. representing bottom dead center (BDC). Likewise,
CAD from 180.degree. to 360.degree. represents an exhaust stroke
with the latter representing TDC. Moreover, CAD from 360.degree. to
540.degree. represents an intake stroke with BDC at the latter.
Furthermore, CAD from 540.degree. to 720.degree. represents a
compression stroke with TDC at the latter. By way of example, the
controller 170--when used in a 6-cylinder engine--would have
ignition taking place every 120.degree. of crankshaft 153 rotation,
that is to say three ignitions per every revolution of ICE 150.
Thus, when ignition has taken place each of the six cylinders one
time, the crankshaft 153 has rotated twice to traverse 720.degree.
of rotary movement. Likewise, if ICE 150 were configured as a
4-cylinder engine, the ignition would take place every 180.degree.
of crankshaft 153 rotation.
[0027] In one form, one of the sensors S may be a crank sensor to
monitor the position or rotational speed of the crankshaft 153. The
data acquired from such a crank sensor is routed to the controller
170 for processing in order to determine fuel injection timing and
other ICE 150 parameters, including ignition timing for those
circumstances (such as cold startup, and the ensuing warm-up) where
a spark ignition device is being used. Sensors S such as the crank
sensor may be used in combination with other sensors S (such as
those associated with valve 157, 158 position) to monitor the
relationship between the valves 157, 158 and pistons 162 in ICE 150
configurations with variable valve timing. Such timing is useful in
CI modes of operation of ICE 150 in that it can close the exhaust
valves 158 earlier in the exhaust stroke while closing the intake
(or inlet) valves 157 earlier in the intake stroke; such operation
as implemented by controller 170 can be used to adjust the
effective compression ratio of ICE 150 in order to obtain the
required temperature and pressure associated with CI combustion.
Likewise, when SI combustion is required, the controller 170 may
instruct the valves 157, 158 to reduce the compression ratio
consistent with an SI mode of operation. Furthermore, the
controller 170 may--depending on the need of ICE 150--provide
auxiliary sparking through SI driver 170G for fuel preparation
(such as the generation of free radicals in the air-fuel mixture).
Sensed input (such as that from various locations within ICE 150,
including CAD from the crankshaft 153, as well as those from
driver-based input such as the accelerator of guidance apparatus
140) may be used to provide load indicia Likewise, in addition to
suitable adjustment of the valves 157, 158, balanced fuel delivery
from each of the enriched product tanks 250, 260 with pressurizing
forces provided by one or more fuel pumps 270 may be achieved by
controller 170 depending on if ICE 150 is in a CI mode or an SI
mode of operation.
[0028] In one form, the fuel injection pressures generated by the
fuel system 200 may be up to about 500 bar for gasoline direct
injection, and up to about 2500 bar for common rail diesel
injection where this higher injection pressure is used to expand
the operating region of diesel-based CI engines in that it
facilitates premixed CI combustion. In so doing, this latter
pressure increase for diesel fuel-based engines may offset the
needed robustness of construction and reductions in compression
ratio and fuel ignition delay. Although there is only pump 270
shown (immediately upstream of the ICE 150) in an attempt to keep
visual clarity within the figure, it will be appreciated that
additional pumps 270 may be placed in other locations within
conduit 210 in order to facilitate the flow of fuel through the
fuel system 200, and that all such variants are within the scope of
the present disclosure. In addition, the pressure of the fuel being
introduced via pump 270 can be varied, and as such may be varied by
controller 170 to regulate overall fuel system 200 performance. For
instance, higher injected fuel pressures can promote a more
thorough octane-enhanced adsorption process.
[0029] The controller 170 may be implemented using model predictive
control schemes such as the supervisory model predictive control
(SMPC) scheme or its variants, or such as multiple-input and
multiple-output (MIMO) protocols, where inputs include numerous
values associated with the various measurements that may be
acquired by sensors S, as well as of estimated values (such as from
the lookup tables or calculated algorithmically) based on
parameters stored in ROM 130C or RAM 130D or the like. In that way,
an output voltage associated with the one or more sensed values
from sensors S is received by the controller 170 and then digitized
and compared to a predetermined table, map, matrix or algorithmic
value so that based on the differences, outputs indicative of a
certain operating environment for ICE 150 are generated. These
outputs can be used for adjustment in the various components the
operation of which falls within the purview of the controller 170,
such as the remaining components associated with fuel system 200,
as well as for adjusting whether fuel delivered from the fuel
system 200 to the combustion chamber 156 corresponds to a bypass
condition (as is discussed in more detail elsewhere within the
present disclosure) of the ICE 150 or an adsorption condition
environment of the ICE 150.
[0030] As mentioned above, in one form, controller 170 may be
preloaded with various parameters (such as atmospheric pressure,
ambient air temperature and flow rate, exhaust gas temperature and
flow rate or the like) into a lookup table that can be included in
ROM 170C or RAM 170D. In another form, controller 170 may include
one or more equation- or formula-based algorithms that permit the
processor 170B to generate a suitable logic-based control signal
based on inputs from various sensors S, while in yet another form,
controller 170 may include both lookup table and algorithm features
to promote its monitoring and control functions. Regardless of
which of these forms of data and computation interaction are
employed, the controller 170--along with the associated sensors S
and conduit 210--cooperate such that as an operating load on the
ICE 150 varies, a suitable adjustment of the market fuel M that is
present in the onboard fuel supply tank 220 may be made to provide
the amount of octane or cetane enrichment needed for such operating
load by mixing the onboard market fuel M with one or the other of
the high-octane or high-cetane product fuels from the enriched
product tanks 250, 260.
[0031] One operational parameter of ICE 150 that may be preloaded
into or generated by controller 170 is the mean effective pressure
(MEP). In one form, MEP may be used to correlate ICE 150 operating
regimes to fuel needs and the various forms of multiple-late
injection strategies discussed previously for various CI mode
configurations. MEP--including its variants indicated mean
effective pressure (IMEP), brake mean effective pressure (BMEP) or
friction mean effective pressure (FMEP)--provides a measure of the
ability of a particular ICE 150 to do work without regard to the
number of cylinders 152 or displacement of such cylinders 152.
Moreover, it provides a measure of the pressure corresponding to
the torque produced so that it may be thought of as the average
pressure acting on a piston 162 during the different portions of
its inlet, compression, ignition and exhaust cycles. In fact, MEP
is often considered a better parameter than torque to compare
engines for design and output because of its independence from
engine speed or size. As such, MEP provides a better indicator than
other metrics (such as horsepower) for engines in that the torque
produced is a function of MEP and displacement only, while
horsepower is a function of torque and rpm. Thus, for a given
displacement, a higher maximum MEP means that more torque is being
generated, while for a given torque, a higher maximum MEP means
that it is being achieved from a smaller ICE 150 Likewise, higher
maximum MEP may be correlated to higher stresses and temperatures
in the ICE 150 which in turn provide an indication of either ICE
150 life or the degree of additional structural reinforcement.
Significantly, extensive dynamometer testing, coupled with suitable
analytical predictions, permit MEP to be well-known for modern
engine designs. As such, for a CI mode, MEP values of about 7.0 bar
to about 9.0 bar are typical at engine speeds that correspond to
maximum torque (around 3000 rpm), while for naturally aspirated
(that is to say, non-turbocharged) SI modes, MEP values of about
8.5 bar to about 10.5 bar are common, while for turbocharged SI
modes, the MEP might be between about 12.5 bar and about 17.0
bar.
[0032] Likewise, MEP values may be determined for various
load-related operating regimes for ICE 150. Such operating regimes
may include low power or load (including, for example, engine
idling conditions) that in one form corresponds to a MEP of up to
about 1.0 bar, in another form of an MEP of up to about 2.0 bar.
Likewise, such operating regimes may include normal (or medium)
power or load that is one form corresponds to a MEP of between
about 2.0 bar to about 5.0 bar, in another form of an MEP of
between about 2.0 bar and about 6.0 bar, in another form of an MEP
of between about 2.0 bar and about 7.0 bar. Moreover, such
operating regimes may include a high power or load that is one form
corresponds to a MEP of about 7.0 bar and above, in another form of
an MEP of about 8.0 bar and above, in another form of an MEP of
about 9.0 bar and above, and in another form of an MEP of about
10.0 bar and above.
[0033] As will be understood, these and other MEP values may be
input into a suitably-mapped set of parameters through load-speed
mapping or the like that may be stored in a memory accessible
location (such as the lookup tables mentioned previously) so that
these values may be used to adjust various ICE 150 operating
parameters, as well as for the controller 170 when acting in a
diagnostic capacity. In such case, it may work in conjunction with
some of the sensors S, including those that can be used to measure
cylinder 152 volume (such as through crankshaft 153 angle or the
like).
[0034] Referring again to FIG. 3, in one form, the solvent supply
230 is a part of a closed-loop such that the solvent V can be
reused. Within the present context, a closed-loop solvent approach
includes those configurations where the solvent V that is used to
desorb the adsorbate A can be regenerated and substantially
recaptured for reuse rather than relying on a regular addition of
solvent V from an external supply. Being closed-loop does not
necessitate complete fluid isolation between the solvent V that is
routed through solvent conduit 238 and the onboard flow of market
fuel M that is routed through conduit 210. In fact, as described
elsewhere, fluid interaction between the solvent V traversing
conduit 238 and the onboard fuel traversing conduit 210--while each
defining different starting and ending locations from one
another--takes place at the reaction chambers 242, 244 that act as
a common receiving location for the respective fluids. As such, a
small amount of the fluid that makes up solvent V may be permitted
to escape through the common space defined by the reaction chambers
242, 244 and still be deemed to be within the scope of a
closed-loop solvent architecture.
[0035] To accomplish this closed-loop retention of the desorbing
solvent V, a solvent regeneration unit 236 is formed as part of
solvent supply 230 to permit the solvent V to be separated and
returned to the tank 232 through solvent conduit 238 in a one-step
process. In one form, the solvent regeneration unit 236 may operate
by liquid-liquid extraction (also referred to as solvent
extraction), where the desorbing solvent V is separated through
combination with another immiscible solvent such that a multilayer
compound develops based on differences in their solubilities. In
another form, the solvent regeneration unit 236 may operate by
extractive distillation. Such extractive distillation may be
especially useful in situations where the difference in volatility
between the solvent V and the desorbate D is small. In this latter
form, a relatively non-volatile (that is to say, high boiling
point) separation solvent is introduced into the solvent supply 230
in such a way to cause the relative volatilities to change between
it and the desorbing solvent V such that each of them may be
subsequently separated by conventional distillation activities.
[0036] Regardless of how the solvent V is regenerated within the
solvent supply 230, the solvent elution-based process as discussed
herein allows the solvent V to wash the adsorbate A from the
reaction chambers 242, 244. In one form, the solvent V is made to
flow past the adsorbate A and adsorbent 242A, 244A that in one form
defines a surface of the reaction chambers 242, 244 such that the
eluting power of the solvent V forces the displacement of the
adsorbate A from the adsorbent 242A, 244A. Thus, the use of solvent
V such as ethylene glycol, propylene carbonate or the like is such
that when the solvent V is circulated into the separation unit 240
through the solvent supply 230, the high affinity of such solvent V
for the adsorbate A portion of the market fuel M that is formed on
the adsorbent 242A, 244A, coupled with the low affinity of the
solvent V for the material that makes up the adsorbent 242A, 244A,
promotes a significant elution force that in turn causes
displacement of such adsorbate A from the adsorbent 242A, 244A. In
one form, any excess solvent V remaining on the adsorbent 242A,
244A within the reaction chambers 242, 244 may be recovered by
methods such as heating the adsorbent 242A, 244A or passing air or
steam to evaporate the solvent V followed by condensation.
[0037] As a result of the reaction between the adsorbate A and the
solvent V that is being introduced from the solvent supply 230 to
the separation unit 240, at least a portion of the adsorbed
compounds or related agents that are on the exposed one of the
reaction chambers 242, 244 are released in the form of desorbate D.
After this, the solvent V and liberated desorbate D may be carried
away through the conduit 238 that makes up the solvent supply 230
in order to have the solvent V regenerated. This regeneration
results in a separation of the solvent V from the desorbate that is
now a suitable octane-enriched or cetane-enriched fuel component
E.sub.O, E.sub.C. The controller 170 may then cooperate with
conduit 210 to ensure that the octane-enriched or cetane-enriched
fuel component E.sub.O, E.sub.C is introduced into the combustion
chamber 156 if the driving cycle or limited supply of
suitably-enriched fuel components within the respective enriched
product tanks 250, 260 warrants it, or otherwise routed to a
respective one of the enriched product tanks 250, 260 where such
fuel component can be stored until needed.
[0038] In one form, a batch-like processing approach may be made to
take place within the separation unit 240 where the pair of
reaction chambers 242, 244 are placed in fluid communication with
the solvent supply 230 such that the market fuel M that becomes
adsorbed in a respective one of the reaction chambers 242, 244 may
be subsequently desorbed by the chemical interaction of the solvent
V in the solvent supply 230 as previously discussed. By having at
least two reaction chambers 242, 244, the separation unit 240 may
be operated in a parallel manner such that while one of the
reaction chambers 242, 244 is being used with its respective
adsorbent 242A, 244A to preferentially capture the adsorbate A, the
other of the reaction chambers 242, 244 may be exposed to the
solvent V from the solvent supply 230 in order to perform the
desorbing or elution operation, after which the roles of the two
chambers 242, 244 are reversed through manipulation by controller
170 of valves (not shown) that make up part of conduit 238, 210.
After exposure of the adsorbate A to the solvent V such that both
the desorbate D and portions of the solvent V are removed from the
separation unit 240, the respective one of the adsorption chambers
242, 244 is regenerated and ready for another batch of incoming
market fuel M for processing. This removal of the solvent V and
adsorbate A has the tendency of keeping the adsorption chambers
242, 244 at a mild temperature, which is beneficial in that it
avoids the need to reheat the first and second reaction chambers
242, 244 during each regeneration stage. Significantly, the use of
solvent V means that the need to use heating as a way to desorb the
adsorbate A can be avoided, thereby reducing the number and
complexity of components used with or as part of the fuel system
200. In a related way, when the eluent (solvent V) and the eluate
(adsorbate A) are separated remotely from the reaction chambers
242, 244 (such as when taking place in solvent regenerator 236),
the reaction chambers 242, 244 are further kept at a mild
temperature, which eliminates the need to re-heat such chambers
during each regeneration stage.
[0039] Eventually, the adsorbent 242A, 244A reaches a state where
it can no longer capture any additional adsorbate A; resulting in a
saturated state for the adsorbent 242A, 244A. The controller 170
can be used in conjunction with one or more of the sensors S to
determine the amount of adsorbate A production within the fuel
system 200, particularly as it relates to the desired degree of
saturation. For example, by detecting a concentration difference
between the market fuel M stream that is entering into the
separation unit 240 and that leaving the separation unit 240, the
logic contained within the controller 170 may determine that a
certain value of such concentration difference can be correlated to
a degree of adsorbate A saturation of the adsorbent 242A, 244A.
Regardless of the mechanism used, when saturated adsorbent 242A,
244A is reached, the controller 170 adjusts various valves that are
formed within conduit 210 in order to selectively adsorb or desorb
the adsorbate A. Within the present context, the adsorbent 242A,
244A is considered to be unsaturated when it is still capable
capturing a measurable quantity of the adsorbate A.
[0040] In using the solvent supply 230, the controller 170 may
instruct batch-based switching between the two chambers 242, 244
through one of three different techniques. In a first technique, a
sensor S is connected to the exit of the first reaction chamber 242
such that when the inlet and outlet liquid streams of the first
reaction chamber 242 have an equal aromatic content as detected by
sensor S (which in turn provides indicia of saturation in that no
additional changes in the aromatic concentration are occurring),
the controller 170 in response to such an acquired signal switches
the market fuel M that is being delivered from supply tank 220 to
the second reaction chamber 244. In a second technique, a timer is
connected to the controller 170 to allow it to open and close at
certain time intervals (for example every 15 minutes) where the
time intervals depend on the adsorbent 242A, 244A size and rate of
the adsorption. In a third technique, sensor S may be a temperature
sensor such that once the temperature at the respective reaction
chamber 242, 244 is no longer increasing (which in turn provides
indicia of no further heat release due to adsorption), the
controller 170 switches the fuel flow from the first reaction
chamber 242 to the second reaction chamber 244. Thus, under such
batch-based operation, the two-chamber construction of the
separation unit 240 is such that while adsorption of a portion of
the market fuel M is taking place in reaction chamber 242, any
adsorbent 242A, 244A that was previously saturated in the other
reaction chamber 244 is regenerated by exposure of the adsorbate A
to the solvent V. As mentioned previously, with a different choice
in adsorbent 242A, 244A in the reaction chambers 242, 244, a
cetane-rich adsorbate A.sub.C (rather than an octane-rich adsorbate
A.sub.O, both of which are shown generally as residing within the
volumetric space defined by the first and second reaction chambers
242, 244) can be formed in a comparable manner. For example, in one
form, materials such as Carbopack B (manufactured by Supelco Inc.
of Bellefonte, Penn.) and graphitizied carbon black may be used to
provide a cetane-attracting functional-group adsorbent.
[0041] In one form, the first of the reaction chambers 242 is sized
and shaped to fluidly receive an aromatic (that is to say,
octane-rich) compound contained within the market fuel M such that
contact of the aromatic on the surface of reaction chamber 242
results in the creation of the octane-rich adsorbate A.sub.O for
OOD. It will be appreciated that related functionality fuel
components such as oxygenates or double bond-based alkyls may also
fall within the category of compounds or fuel components that can
provide OOD. In such form, the preferential action of a suitable
functional group contained within or formed on the surface of the
adsorbent 242A that makes up the reaction chamber 242 provides the
necessary separation. In this form, the operation of the tank 232,
solvent regeneration unit 236 and conduit 238 causes the adsorbate
A to be desorbed and released to an octane-rich one of the enriched
product tanks 250, 260 for subsequent use in the combustion chamber
156 in situations where the market fuel M is a higher boiling point
(for example, between about 165.degree. C. and about 350.degree.
C.) diesel-type fuel. With a different choice in adsorbent 242A,
244A (for example, a size selective version) from the solvent
supply 230 being circulated through the reaction chambers 242, 244,
a cetane-rich adsorbate A.sub.C for combustion chamber 156 is
created; such an approach may be used in situations where the
market fuel M is a lower boiling point (for example, between about
ambient temperature and about 200.degree. C.) gasoline-type fuel.
As such, the reaction chambers 242, 244 may--in addition to having
batch processing capability discussed previously through selective
adsorbing and desorbing activities--be set up in stages (not shown)
in the manner previously discussed such that a first stage
preferentially provides one or the other of affinity-based or size
selective-based adsorption while a second stage provides the other
of the size selective--based or affinity-based adsorption. Such
staging may take place sequentially, in either common or separate
housing, in a manner suitable to ensure relatively small volumetric
packaging needed to fit as unobtrusively as possible within vehicle
100. It will be appreciated that the order of separation achieved
by such staging may be affinity-based first and size selective
second, or size selective first and affinity-based second,
depending on the need.
[0042] In one form, the fuel system 200 is particularly configured
to operate on a market fuel M that can provide energy for a CI mode
of operation. Thus, unlike in situations where the boiling range of
the separated fuel stream is within a range that is compatible with
heat exchange values that can be provided by the operation of the
ICE 150 (such as the case when the market fuel M includes
significant gasoline fractions), when the separated stream has low
volatility (that is to say, high boiling point) such as the case
when separating diesel fuel fractions, then the high temperature
needed to perform such regeneration is either not readily available
onboard vehicle 100 or is such that the separated component could
be prone to cracking at the high temperatures required to perform
such regeneration of solvent V. In this way, the solvent V and the
cetane-rich adsorbate A.sub.C may then be separated by a one-step
method in the solvent regeneration unit 236 such as discussed
elsewhere in this disclosure. Such separation may be enhanced by
selecting the solvent V to have much different volatility than the
cetane-rich adsorbate A.sub.C. It will be appreciated that the fuel
system 200--working in conjunction with controller 170--may be
configured to operate in either of both of an OOD mode of operation
or a COD mode of operation depending on one or more of the affinity
and size of the adsorbent 242A, 244A such as those discussed
previously.
[0043] In one form, the solvent supply 230 may be disposed within
the housing or related containment structure that makes up the
separation unit 240, while in another, it may be placed outside
such housing such that as solvent V is needed to perform the
desorbing operation from one or both of the reaction chambers 242,
244, it can be delivered from the solvent supply 230 through
suitable conduit 238 as previously discussed. As with the packaging
used to reduce space for the solvent supply 230, the adsorbent
242A, 244A type may be selected to promote small housing or
containment structure size. In one form, if the adsorbent 242A,
244A employs a high surface area-to-volume ratio by exploiting the
geometry and structure of particles and bed that make up the two
reaction chambers 242, 244, such higher surface area may lead to
higher adsorption capacity and smaller separation unit 240 size as
a way to promote ease of system integration.
[0044] As mentioned previously, various forms of stratified
combustion may lead to the types of LTC that are beneficial to
low-NO.sub.X operation of ICE 150. With regard to the use of OOD or
COD for a CI mode of operation, the fuel may be formed as a hybrid
of a main fuel (for example, gasoline or other low-cetane variant)
and an igniter fuel (for example, diesel or other high-cetane
variant), where the location, frequency and timing of introduction
of each varies by concept or configuration such as those discussed
previously. For example, in one concept, a single high-octane fuel
is introduced via direct injection during a compression stroke. In
such case, the injection of the fuel may take place at a time
relatively retarded from conventional diesel injection timing to
ensure adequate mixing. Since the overall combustion process is
dominated by reactivity-controlled LTC, the resulting NOx and soot
exhaust emissions tend to be very low. In another case, a single
igniter fuel is introduced via direct injection during the
compression stroke in order to promote cold-start and high-load
operation where the overall combustion process is dominated by
diffusion-controlled mixing of the fuel at or near the piston 162
TDC movement. In still another case, a dual injection regime
introduces the main fuel via port fuel injection early in the
compression stroke within the combustion chamber 156 such that it
is fully mixed with a fresh air charge during the intake stroke,
after which the igniter fuel is introduced via direct injection as
a way to control ignitability such that the overall combustion
process is dominated by the spatially well-mixed high-octane fuel
after the ignition of high-cetane fuel. As with the first case
mentioned previously, such operation produces low NOx and soot
emissions, due at least in part to an overall lean mixture. In yet
another case, the main fuel is introduced via direct injection
during the compression stroke, while the igniter fuel is introduced
via direct injection near TDC to enable the ignition control; in
this way, it provides a relatively robust mixture via improved
thermal or spatial stratification. This in turn leads to low
hydrocarbon, NOx and soot formation, at least for relatively low
engine loads.
[0045] In one form, a so-called bypass may be used for intermittent
circumstances associated with various ICE 150 operating
environments (such as cold starts, or where one or both of the two
enriched product tanks 250, 260 may be empty) such that at least a
fraction of the market fuel M from the supply tank 220 is provided
directly to the combustion chamber 156 without entering the
separation unit 240. This bypass operation may be established by
controller 170 to help promote a continuous supply of fuel to ICE
150, where such continuity is particularly useful under these
intermittent operational conditions. In particular, the controller
170 may be used to manipulate various fuel delivery parameters,
such as coolant temperature, exhaust gas temperature, EGR, exhaust
gas re-breathing, level of separated fuels, delivery timing or the
like for such transient conditions. This helps promote wider
operating ranges based on reactivity differences between the
high-octane and high-cetane fuel components. This wider operating
range is especially beneficial with regard to reducing NOx or soot
emissions regardless of factors such as ICE 150 load, operating
temperature, fuel delivery or the like. This in turn reduces the
likelihood of having to make emissions or performance tradeoffs
(such as a soot/NOx tradeoff), where factors such as temperature
and engine equivalence ratio can otherwise force the controller 170
to determine which of two or more competing ICE 150 operating
conditions should be permitted to operate. Such operating range is
also beneficial in that it permits various other fuel injection
strategies to be utilized to enable optimum efficiency, reduced
emissions and improved combustion robustness compared to
conventional SI-based or CI-based cycles, including using EGR,
reduced compression ratios or the like as part of a larger LTC
strategy.
[0046] As previously discussed, in one form the adsorbents 242A,
244A used for the reaction chambers 242, 244 are configured as one
or more functional groups presenting on the surface of the sorbent
material such that they comprise affinity-based sorbents. In
another form, the adsorbents 242A, 244A may separate adsorbates A
by their molecular shape such that they comprise size selective
sorbents. For example, to target high-cetane fuel components, the
design would focus on separating linear or slightly branched
alkanes from aromatics, cyclic and highly branched alkanes. Stated
another way, the sorbents can act in two mechanisms, where in a
first, the adsorbent 242A, 244A is selected to have functional
groups that attract specific molecules such as aromatics, cyclic,
(and oxygenates if present). The linear and slightly branched
molecules (which may include cetane) are not adsorbed and pass
through the pores of one or both of the reaction chamber 242, 244,
depending on their mode of operation. The second mechanism is based
on the difference in the molecules sizes such that linear molecules
(such as n-alkanes) may pass through the relatively porous material
while other molecules which have a larger dynamic diameter (such as
highly-branched alkanes) are hindered from passing through most
pores and accumulate in the adsorption-based reaction chamber 242,
244. In this latter mechanism, a packed bed of size selective
sorbent may be used for COD generation, as linear alkanes with high
CN will go into smaller pores while the other components with
larger molecular size will not, causing these other components to
come out first as a raffinate. Moreover, in configurations where
the adsorbent 242A, 244A acts as a molecular sieve, it may be made
up of more than one particle type or size in order to
preferentially promote the adsorption of a desired species based on
the size of such species. Regardless of the adsorbent 242A, 244A
choice, the performance is optimized on various factors, including
the capacity and selectivity of the adsorbent 242A, 244A, the
concentration ratio of the market fuel M (which provides indicia of
the aromatics fractions), and how fast the solvent V regeneration
and desorption-based removal proceeds.
[0047] Specific surface area (that is to say, the total surface
area of a given substance per unit mass, for example, in m.sup.2/g)
is a valuable metric in assessing the efficacy of an adsorbent such
as adsorbent 242A, 244A. In particular, increasing the specific
surface area of the adsorbent 242A, 244A permits a higher
adsorption capacity. For example, when using activated carbon with
specific surface area ranging in size from 500 to 1500 m.sup.2/g,
the adsorption capacity correspondingly increases, as well as with
the adsorbed molecule type. Thus, adsorbents 242A, 244A with
different specific surface areas can be used to selectively adsorb
one or the other of a desirable component within the market fuel M,
and all such variants are deemed to be within the scope of the
present disclosure. For example, the specific surface area may be
tailored to adsorb low boiling point straight alkanes as a way to
produce the cetane-rich adsorbate A.sub.C that can act as a high
ignition quality booster for the market fuel M in a CI mode of
operation. Likewise, the specific surface area may be tailored to
adsorb aromatics as a way to produce the octane-rich adsorbate
A.sub.O that can act as a high ignition quality booster for the
market fuel M in an SI mode of operation. For instance, to adsorb
certain aromatics, the adsorbent 242A, 244A that makes up the
reaction chambers 242, 244 can be mesoporous (2-50 nm diameter)
activated carbon, which in turn can lead to an average recovery of
about 80%. An example of the anticipated adsorption capacity of
some aromatic components for activated carbon is listed in Table
1.
TABLE-US-00001 TABLE 1 Component mg/g-adsorbent Toluene 15
Naphthalene 45 1-methylnaphthalene 37
[0048] Other natural adsorbents (for example, coconut shell) may
also be used for separating the desired components. In another
form, the surface of the reaction chambers 242, 244 may define one
or more beds that may be made up of more than one adsorbent 242A,
244A in order to preferentially promote the adsorption of a desired
species. Regardless of the adsorbent 242A, 244A bed choice, the
performance is optimized on various factors, including the
adsorbent 242A, 244A capacity and selectivity, the concentration
ratio of the market fuel M (which provides indicia of the aromatics
fractions), and how fast the regeneration and desorption-based
removal proceeds.
[0049] With particular regard to the bypass mentioned previously,
in certain operating environments of ICE 150, it may be necessary
for reliable combustion to not use the separation unit 240, but to
instead use conventional modes of operation such as those
associated with traditional diesel-based CI or gasoline-based SI,
as at startup or other scenarios there are no exhaust gases or hot
radiator fluid available to heat the adsorption cycle, or where
there are no high-cetane or high-octane fuels present in the
enriched product tanks 250, 260. Within the present context, this
operating environment that corresponds to having neither an
adequate amount of heat (such as the residual that accompanies the
ICE 150 combustion process, as well as any supplemental source of
heat such as that associated with an electric heater, separate
combustor or the like) nor onboard supply of cetane-rich or
octane-rich fuel components is referred to as the bypass condition.
In the bypass condition, the controller 170 may direct the supply
of fuel to be conveyed from the market fuel supply tank 220 and
directly to the combustion chamber 156 of ICE 150 so that a
suitable CI or SI mode of operation may be undertaken without
having to rely upon the production or use of the additional
octane-rich or cetane-rich fuel components as produced by the
separation unit 240 and solvent supply 230. Contrarily, an
operating environment that corresponds to having one or both an
adequate amount of heat (such as the residual that accompanies the
ICE 150 combustion process) and onboard supply of cetane-rich or
octane-rich fuel components is referred to as the adsorption
condition; in this latter condition, varying amounts of additional
octane-rich or cetane-rich fuel components may be produced, used in
the combustion process, or both. The bypass condition of ICE 150
means that the bypass may be used to avoid otherwise undesirable
latency periods associated with sudden driving operations in
response to speed or load demands, as well as those related to
temperature or related weather conditions. In such circumstances,
the controller 170 may instruct some or all of the market fuel M
from supply tank 220 to be supplied directly to the combustion
chamber 156, without entering the separation unit 240. The fraction
of bypass can be controlled and manipulated via different methods
such as temperature of the coolant or exhaust gas, level of
separated fuels, time or other variables. Likewise, the controller
170 may in one form optionally mandate that under this bypass
condition, the SI mode of operation be employed, while in another
optional form may permit the CI mode of operation to proceed, such
as those associated with the market fuel supply tanks 220
containing diesel fuel.
[0050] Two examples are presented to highlight when the bypass
operation that may take place when the operating environment of the
ICE 150 is warranted. In a first example, during startup of ICE 150
when insufficient heat is available to properly operate an
adsorption operation within the separation unit 240, the controller
170 works together so that fuel flow to the combustion chamber 156
may partially come from the two enriched product tanks 250, 260,
while the main fuel portion comes from the market fuel supply tank
220. In a second example, if either of the two enriched product
tanks 250, 260 is empty at any time (such as that associated with
unexpected driving cycle conditions, lack of solvent-based elution
of the adsorbate A needed for desorption or other event that would
leave the enriched product tanks 250, 260 empty or nearly empty),
the controller 170 may likewise instruct one or more fuel pumps 270
(only one of which is shown) to pressurize the market fuel M being
delivered from the supply tank 220 directly to the combustion
chamber 156 as a way to at least partially bypass the separation
unit 240 to compensate for the shortage in the enriched product
tank 250 or the enriched product tank 260 where it will be
understood that one or the other of the enriched product tanks 250,
260 is configured to contain an octane-rich fuel component while
the other is configured to contain a cetane-rich fuel component,
depending on whether the adsorbent 242A, 244A that is being
introduced into the reaction chambers 242, 244 is an affinity-based
one or a size selective-based one. Thus, in one form, the enriched
product tank 250 contains a high RON fuel while the enriched
product tank 260 contains a high CN fuel, whereas in another form,
the enriched product tank 250 contains a high CN fuel while the
enriched product tank 260 contains a high RON fuel. In situations
where both cold engine conditions and low enriched product tank
250, 260 levels are present, the bypass may be complete rather than
partial, and may accompany an SI or conventional diesel-based CI
mode of operation as well.
[0051] Having described the subject matter of the present
disclosure in detail and by reference to specific embodiments
thereof, it is noted that the various details disclosed in the
present disclosure should not be taken to imply that these details
relate to elements that are essential components of the various
described embodiments, even in cases where a particular element is
illustrated in each of the drawings that accompany the present
description. Further, it will be apparent that modifications and
variations are possible without departing from the scope of the
present disclosure, including, but not limited to, embodiments
defined in the appended claims. More specifically, although some
aspects of the present disclosure are identified as preferred or
particularly advantageous, it is contemplated that the present
disclosure is not necessarily limited to these aspects.
[0052] It is noted that one or more of the following claims utilize
the term "wherein" as a transitional phrase. For the purposes of
defining features discussed in the present disclosure, it is noted
that this term is introduced in the claims as an open-ended
transitional phrase that is used to introduce a recitation of a
series of characteristics of the structure and should be
interpreted in like manner as the more commonly used open-ended
preamble term "comprising."
[0053] It is noted that terms like "preferably", "generally" and
"typically" are not utilized in the present disclosure to limit the
scope of the claims or to imply that certain features are critical,
essential, or even important to the disclosed structures or
functions. Rather, these terms are merely intended to highlight
alternative or additional features that may or may not be utilized
in a particular embodiment of the disclosed subject matter.
Likewise, it is noted that the terms "substantially" and
"approximately" and their variants are utilized to represent the
inherent degree of uncertainty that may be attributed to any
quantitative comparison, value, measurement or other
representation. As such, use of these terms represent the degree by
which a quantitative representation may vary from a stated
reference without resulting in a change in the basic function of
the subject matter at issue.
[0054] It will be apparent to those skilled in the art that various
modifications and variations can be made to the described
embodiments without departing from the spirit and scope of the
claimed subject matter. Thus it is intended that the specification
cover the modifications and variations of the various described
embodiments provided such modification and variations come within
the scope of the appended claims and their equivalents.
* * * * *